1. Fluid Power Control

2. Introduction to Pneumatics
FLUID POWER
Introduction to Pneumatics
ELECTRO – PNEUMATIC SYSTEM
What shall we cover in this chapter?
a) Use of electrical devices for controlling fluid circuits;
b) Function of electrical devices like push-button switches, limit switches, pressure switches, solenoids, relays and timers and their symbols;
c) Concept of ladder diagram;
d) study of following circuits using electrical control devices :
i) control of a solenoid actuated cylinder using one limit switch;
ii) reciprocation of a cylinder using pressure or limit switches,
iii) two cylinder sequencing circuit using two limit switches.

3. Introduction to Pneumatics
FLUID POWER
Introduction to Pneumatics
Use of electrical devices for controlling fluid circuits:
Upon completion of this chapter, Student should be able to :
Explain the various steps involved in electro pneumatics
List seven basic electrical devices used in electro pneumatics
Describe the constructional details of solenoid valves
Explain the operations of control devices like limit switches, sensors, timers , counters and pressure switches
Differentiate between capacitive and inductive proximity sensors
Differentiate between dominant on and off latching circuits
Design single actuator electro pneumatic circuits
Design a sequence circuits using two and three cylinders

4. Introduction to Pneumatics
FLUID POWER
Introduction to Pneumatics
ELECTRO – PNEUMATIC SYSTEM
In Electro pneumatic controls, mainly three important steps are involved:
 Signal input devices -Signal generation such as switches and contactor, Various types of contact and sensors
 Signal Processing – Use of combination of Contactors of Relay or using Programmable Logic Controllers
 Signal Out puts – Out puts obtained after processing are used for activation of solenoids, indicators or audible alarms

5. Introduction to Pneumatics
FLUID POWER
Introduction to Pneumatics
ELECTRO – PNEUMATIC SYSTEM: devices
Seven basic electrical devices commonly used in the control of fluid power systems are :
1. Manually actuated push button switches
2. Limit switches
3. Pressure switches
4. Solenoids
5. Relays
6. Timers
7. Temperature switches
** All the switches can be wired either ‘NO’ or ‘NC’ type. A ‘NO’ switch is one in which no electric current can flow through the switching element until the switch is actuated.

6. Introduction to Pneumatics
FLUID POWER
Introduction to Pneumatics
ELECTRO – PNEUMATIC SYSTEM: devices
Manually actuated push button switches NO NC

7. Introduction to Pneumatics
FLUID POWER
Introduction to Pneumatics
ELECTRO – PNEUMATIC SYSTEM: devices
Manually actuated push button switches
Function
Starting and stopping of operation of machinery
Closing or opening an electric control circuit
Providing manual override when the emergency arises.
Type
Momentary push button
Maintained contact or detent

8. Introduction to Pneumatics
FLUID POWER
Introduction to Pneumatics
ELECTRO – PNEUMATIC SYSTEM: devices
Manually actuated push button switches CO

9. Introduction to Pneumatics
FLUID POWER
Introduction to Pneumatics
ELECTRO – PNEUMATIC SYSTEM: devices
LIMIT
SWITCH
Manually / Mechanically Actuated.

10. Introduction to Pneumatics
FLUID POWER
Introduction to Pneumatics
ELECTRO – PNEUMATIC SYSTEM: devices
LIMIT SWITCHES
Any switch that is actuated due to the position of a fluid power component (usually a piston rod or hydraulic motor shaft or the position of load is termed as limit switch.
The actuation of a limit switch provides an electrical signal that causes an appropriate system response.

11. Introduction to Pneumatics
FLUID POWER
Introduction to Pneumatics
ELECTRO – PNEUMATIC SYSTEM: devices
LIMIT SWITCHES
Limit switches may also be provided at the ends of a cylinder

12. Introduction to Pneumatics
FLUID POWER
Introduction to Pneumatics
ELECTRO – PNEUMATIC SYSTEM: devices
PRESSURE SWITCHES
Function
How does it work?

13. Introduction to Pneumatics
FLUID POWER
Introduction to Pneumatics
ELECTRO – PNEUMATIC SYSTEM: devices
SOLENOID
What is a SOLENOID?
How does it work?
Types

14. Introduction to Pneumatics
FLUID POWER
Introduction to Pneumatics
ELECTRO – PNEUMATIC SYSTEM: devices
Symbol of SOLENOID

15. Introduction to Pneumatics
FLUID POWER
Introduction to Pneumatics
ELECTRO – PNEUMATIC SYSTEM: devices
RELAYS
What is a Relay Switch?

16. Introduction to Pneumatics
FLUID POWER
Introduction to Pneumatics
ELECTRO – PNEUMATIC SYSTEM: devices
RELAYS
How does it work?

17. Introduction to Pneumatics
FLUID POWER
Introduction to Pneumatics
ELECTRO – PNEUMATIC SYSTEM: devices
RELAYS
Characteristics

18. Introduction to Pneumatics
FLUID POWER
Introduction to Pneumatics
ELECTRO – PNEUMATIC SYSTEM: devices
TEMPERATURE SWITCHES
Function
How does it work?

19. Introduction to Pneumatics
FLUID POWER
Introduction to Pneumatics
ELECTRO – PNEUMATIC SYSTEM: Concept of LADDER DIAGRAM

20. Introduction to Pneumatics
FLUID POWER
Introduction to Pneumatics
ELECTRO – PNEUMATIC SYSTEM: Concept of LADDER DIAGRAM

21. Introduction to Pneumatics
FLUID POWER
Introduction to Pneumatics
ELECTRO – PNEUMATIC SYSTEM: Electro-Pneumatic circuits
 Control of a solenoid actuated cylinder using one limit switch

22. Introduction to Pneumatics
FLUID POWER
Introduction to Pneumatics
ELECTRO – PNEUMATIC SYSTEM: Electro-Pneumatic circuits
 Reciprocation of a cylinder using pressure switches

23. Introduction to Pneumatics
FLUID POWER
Introduction to Pneumatics
ELECTRO – PNEUMATIC SYSTEM: Electro-Pneumatic circuits
 Reciprocation of a cylinder using limit switches

24. Introduction to Pneumatics
FLUID POWER
Introduction to Pneumatics
ELECTRO – PNEUMATIC SYSTEM: Electro-Pneumatic circuits
 Two cylinder sequencing circuit using two limit switches

26. Introduction to Pneumatics
FLUID POWER
Introduction to Pneumatics
ELECTRO – PNEUMATIC SYSTEM: devices
TIMERS
Function
How does it work?